With the advancement of information communication technologies, various wireless communication technologies have recently been developed. Among the wireless communication technologies, a wireless local area network (WLAN) is a technology whereby high-speed Internet access is possible in a wireless fashion in homes or businesses or in a region providing a specific service by using a portable terminal such as a personal digital assistant (PDA), a laptop computer, a portable multimedia player (PMP), etc.
It is assumed that WLAN communication conforming to the institute of electrical and electronics engineers (IEEE) 802.11 standard is achieved in a region called a basic service set (BSS). A BSS region may differ according to a propagation characteristic of a wireless medium, and thus has an ambiguous boundary. The BSS can be classified into two structures, i.e., an independent BSS (IBSS) and an infra-structured BSS. The former is to constitute a self-contained network and denotes a BSS in which access to a distribution system (DS) is not allowed. The latter includes one or more access points (APs), DSs, etc., and generally denotes a BSS in which the APs are used in all communication processes including communication between stations.
A station (STA) which intends to access to a wireless network can use two schemes to find an accessible wireless network (e.g., BSS or IBSS), that is, a candidate AP or the like.
A first scheme is passive scanning using a beacon frame transmitted from an AP (or STA). That is, the STA which intends to access to the wireless network can find an accessible BSS or IBSS by receiving the beacon frame periodically transmitted from the AP or the like which manages a corresponding BSS (or IBSS).
A second scheme uses active scanning. In this scheme, the STA which intends to access to the wireless network first transmits a probe request frame. Upon receiving the probe request frame, the STA or the AP responds by transmitting a probe response frame.
As a special type of network, a mesh network is defined in the WLAN. The mesh network may be defined as a network which supports direct communication between a plurality of wireless devices having a relay function without via an AP. Functionally, a distribution system (DS) of the AP can be replaced with an interoperable wireless link or a multi-hop path between the plurality of wireless devices. According to the mesh network, any one of the wireless devices can establish an interoperable peer-to-peer wireless link with other neighboring wireless devices and/or APs. Therefore, there is an advantage in that a wireless connection can be more flexibly established.
In the mesh network, one wireless device can be connected to a plurality of other wireless devices and thus can have a plurality of communication paths. Such a communication path between the wireless devices is also referred to as a wireless mesh link, or simply, a mesh link or a peer link. Such a wireless device is referred to as mesh point (MP), but may also be referred to other equivalent terminologies. Among MPs, an MP performing not only the aforementioned relay function but also an AP function is referred to as a mesh access point (MAP).
Such a mesh network has many advantages, e.g., flexibility of network implementation, reliability caused by a detour path, and reduction of power consumption resulted from a decreased communication distance, etc. More specifically, by using the mesh network, a network can be flexibly implemented between MPs in a place where there is no existing communication network. In addition, the mesh network can ensure a plurality of detour paths due to interconnections among a plurality of MPs. Therefore, even if one MP is erroneous, data can be transmitted through another path. Further, since the mesh network can perform communication via a neighboring MP even if a coverage of one MP is not large enough, telecommunication can be achieved with low power.